JP5717497B2 - Oscillator - Google Patents

Description

  The present invention relates to an oscillator, and more particularly to an oscillator capable of improving heat cycle resistance and obtaining good frequency temperature characteristics.

[Description of Prior Art]
2. Description of the Related Art Conventionally, there is an oven-controlled crystal oscillator (OCXO) that includes a thermostatic chamber and reduces the change in output frequency even when the ambient temperature changes.
Normally, the OCXO controls the temperature of the thermostatic chamber so as to operate at a zero temperature coefficient (ZTC) point at which the frequency change due to the temperature change of the crystal resonator is minimum. At the ZTC point (ZTC temperature), even if the frequency-temperature characteristic is stable and the temperature changes, the frequency change due to the change is small.

Conventionally, a thermostat is controlled so that the ZTC temperature is about 10 ° C. higher than the upper limit temperature of the set use environment temperature, and the ZTC temperature is close to the ZTC temperature.
For example, when the operating environment temperature is −20 ° C. to 70 ° C., a crystal resonator having a ZTC temperature of 80 ° C. to 90 ° C. is used, and the temperature is controlled to 80 ° C. to 90 ° C. so as to be the ZTC temperature in a constant temperature bath. .

  In OCXO, a crystal resonator and an electronic component are connected and fixed to a terminal pattern or wiring pattern formed on a substrate by soldering.

[Related technologies]
As a technique related to the oscillator, Japanese Patent Application Laid-Open No. 2004-48686 “Highly stable piezoelectric oscillator” (Toyo Communication Equipment Co., Ltd., Patent Document 1), Japanese Patent Application Laid-Open No. 2000-183649 “Highly stable piezoelectric oscillator” (Toyo Communication Equipment) Corporation, Patent Document 2).

In Patent Document 1, the OCXO case (first thermostat) is set to a temperature lower than the second thermostat provided outside the OCXO, and the second thermostat is heated by a Peltier element. A piezoelectric oscillator is described in which one thermostat is controlled to be cooled to a temperature lower than that of the second thermostat, and heat of the first thermostat is transferred to the second thermostat.
Patent Document 2 describes a piezoelectric oscillator that controls the temperature of an OCXO thermostat lower than the ambient temperature.

JP 2004-48686 A JP 2000-183649 A

  However, in the conventional OCXO, a temperature change from the ambient temperature to the control temperature of the thermostatic chamber occurs every time the power is turned on / off, and in a usage environment in which the power is turned on / off repeatedly, the mounting solder is distorted by the heat cycle. Concentration, cracks in the solder occurred, and there was a problem that long-term reliability was not sufficient.

  For example, when the use environment temperature is −20 ° C., a temperature change of −20 ° C. to 90 ° C. occurs every time the power is turned on / off, and a temperature difference (ΔT) of 110 ° C. is generated, so that the solder is easily stressed.

  Note that Patent Document 1 describes that the first thermostat is simply cooled by using a Peltier element and the second thermostat is heated. The use environment of OCXO is not appropriately controlled by cooling or heating.

  The present invention has been made in view of the above circumstances, and it is possible to suppress the occurrence of solder cracks by reducing temperature changes associated with heat cycles, improve long-term reliability, and obtain a stable output frequency. An object of the present invention is to provide an oscillator that can be used.

  The present invention for solving the problems of the above-mentioned conventional example is an oscillator including a crystal oscillator with a warm bath, provided with a Peltier element that performs heating or cooling according to an electric current, and a Peltier element provided on a substrate. A Peltier element control circuit to be controlled, a crystal oscillator with a thermostatic chamber, a case that hermetically encloses the Peltier element and the Peltier element control circuit, and the Peltier element is sandwiched between the crystal oscillator with a thermostatic chamber and the substrate And a crystal oscillator with a thermostatic chamber having a zero temperature coefficient point of 45 ° C. to 55 ° C., and a temperature control circuit for controlling the temperature of the thermostatic chamber to be the zero temperature coefficient point of the crystal resonator And the Peltier element control circuit controls the current of the Peltier element so that the temperature in the case is lower than the zero temperature coefficient point of the crystal resonator in the range of 10 ° C. to 25 ° C.

  In the oscillator according to the present invention, the Peltier device control circuit controls the temperature in the case in a range of 25 ° C to 35 ° C.

  Further, according to the present invention, in the oscillator, the Peltier element control circuit includes a temperature sensor that detects a temperature in the case, and when the detected temperature is higher than a set temperature range, the Peltier element is in the case. The current is controlled so as to cool the air.

  Further, in the oscillator according to the present invention, when the detected temperature is lower than a preset temperature range, the Peltier element control circuit controls the current so that the Peltier element heats the inside of the case. It is said.

  Further, according to the present invention, in the oscillator, the Peltier device control circuit stores control data for controlling a current corresponding to the set temperature range and the detected temperature, and is based on the control data corresponding to the detected temperature. It is characterized by controlling the current.

  Further, the present invention is characterized in that in the oscillator, the inside of the case is in a vacuum or a state close to a vacuum.

  According to the present invention, there is provided an oscillator including a crystal oscillator with a warm bath, a Peltier element that performs heating or cooling according to a current, a Peltier element control circuit that is provided on a substrate and controls the Peltier element, and a constant temperature A crystal oscillator with a bath, a Peltier device, and a case for hermetically enclosing the Peltier device control circuit, and the Peltier device is sandwiched and mounted between the crystal oscillator with a thermostat and the substrate, and the crystal oscillator with a thermostat Is provided with a crystal resonator having a zero temperature coefficient point of 45 ° C. to 55 ° C., and a temperature control circuit that controls the temperature of the thermostatic chamber to be the zero temperature coefficient point of the crystal resonator, Since the oscillator controls the current of the Peltier element so that the temperature in the case is lower in the range of 10 ° C. to 25 ° C. than the zero temperature coefficient point of the crystal unit, the operating temperature of the OCXO is lowered. The temperature difference in the heat cycle can be reduced, cracks in the mounted solder are less likely to occur and long-term reliability can be improved, and the temperature in the case corresponding to the periphery of the OCXO is 10 ° C. higher than the target temperature of the OCXO. By setting the temperature in the range of ˜25 ° C., there is an effect that the temperature control of the OCXO can be performed efficiently and accurately, and the temperature frequency characteristics of the output frequency can be improved.

  Further, according to the present invention, the Peltier element control circuit includes a temperature sensor that detects the temperature in the case. When the detected temperature is higher than the set temperature range, the Peltier element cools the inside of the case. Thus, since the above-described oscillator for controlling current is used, when the temperature in the case corresponding to the periphery of the OCXO is high, there is an effect that the inside of the case can be cooled to stabilize the temperature control of the OCXO.

  Further, according to the present invention, the Peltier element control circuit is the oscillator that controls the current so that the Peltier element heats the inside of the case when the detected temperature is lower than a preset temperature range. When the temperature in the case corresponding to the periphery of the OCXO is low, there is an effect that the temperature in the OCXO can be efficiently controlled by heating the inside of the case.

  Further, according to the present invention, the Peltier device control circuit stores control data for controlling current corresponding to the set temperature range and detected temperature, and the current is controlled based on the control data corresponding to the detected temperature. Since the oscillator to be controlled is used, the control data can be rewritten according to the mounted crystal oscillator, and there is an effect that it can be applied to various crystal resonators having different zero temperature coefficient points.

  In addition, since the above-mentioned oscillator is set in a vacuum or a state close to vacuum, the effect of the temperature of the external environment on the OCXO can be reduced, and the output frequency can be further stabilized.

It is a schematic sectional explanatory drawing which shows the structure of the oscillator which concerns on embodiment of this invention. FIG. 4 is a schematic explanatory diagram of a Peltier element control circuit mounted on a Peltier element temperature control circuit board 4. It is explanatory drawing which shows the example of a temperature characteristic of an AT cut crystal resonator. It is a flowchart which shows the process of the control part of a Peltier device control circuit.

Embodiments of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
The oscillator according to the embodiment of the present invention includes an OCXO using a crystal resonator having a ZTC temperature of 45 ° C. to 55 ° C. in a sealed case, a Peltier element that adjusts the temperature in the case, and a control of the Peltier element. And a substrate on which a Peltier element control circuit is mounted, the Peltier element is provided in close contact between the OCXO and the substrate, and the OCXO controls the oven to the ZTC temperature of the crystal resonator. The Peltier device is controlled so that the temperature in the case is 25 ° C. to 35 ° C., which is about 10 ° C. to 20 ° C. lower than the ZTC temperature. To prevent solder cracks and improve heat cycle resistance, and the constant temperature of OCXO regardless of the ambient temperature Control efficiently and accurately even it is possible to stabilize the output frequency by performing a further, but that can increase in temperature is to be applied to the device or devices, such as a problem.

[Configuration of Oscillator According to this Embodiment: FIG. 1]
The configuration of the oscillator according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional explanatory view showing a configuration of an oscillator according to an embodiment of the present invention.
As shown in FIG. 1, an oscillator (present oscillator) according to an embodiment of the present invention includes an OCXO 1, a Peltier element 3, and a Peltier element temperature control circuit board 4 inside an outer case 6 sealed by a lid 7. The Peltier element 3 is mounted in a state of being sandwiched between the OCXO 1 and the Peltier element temperature control circuit board 4.

The OCXO 1 is fixed to the Peltier element temperature control circuit board 4 with pins and solder.
The Peltier element temperature control circuit board 4 is fixed to a lid 7 that seals the outer case 6 with pins 8 fixed to the board 4 with solder 5.

The OCXO 1 includes an inner case 2 corresponding to a sealed thermostat (oven), and in the inner case 2, similarly to a general OCXO, a crystal resonator, an oscillation circuit, a heating element, a temperature sensor, and a temperature control circuit Etc. are provided.
As a feature of this oscillator, the OCXO1 crystal resonator has a ZTC temperature of 45 ° C. to 55 ° C. That is, in this oscillator, a crystal resonator having a ZTC temperature lower by about 35 ° C. than that of the conventional one is mounted, and the temperature difference in the heat cycle is reduced to prevent the occurrence of solder cracks. The characteristics of the crystal unit of OCXO1 will be described later.
In this oscillator, the temperature control circuit of the OCXO 1 controls the heating element so that the temperature in the inner case 2 (a constant temperature bath) is close to the ZTC temperature of the crystal resonator.

The Peltier element 3 is an element that utilizes a phenomenon in which heat is absorbed and heat is generated at the joint when two different metals (or semiconductors) are electrically connected in series and a current is passed. Therefore, if the direction of the current is reversed, heat generation and heat absorption are reversed.
The Peltier element 3 of this oscillator is provided in close contact between the OCXO 1 and the Peltier element temperature control circuit board 4, and when the Peltier element temperature control circuit board 4 side is cooled, heat is released to the OCXO 1 side. Thus, OCXO1 can be efficiently heated.

The Peltier element temperature control circuit board 4 is a board on which the Peltier element control circuit is mounted.
The Peltier element control circuit controls the heat absorption or heat generation of the Peltier element 3 by controlling the current flowing through the Peltier element 3 so as to control the inside of the outer case 6 within a specific temperature range.

  As a feature of this oscillator, the Peltier device control circuit controls the temperature inside the outer case 6 to a temperature that is 10 ° C. or more lower than the ZTC temperature of the crystal resonator. Thus, by controlling the temperature inside the outer case 6 to be 10 ° C. or more lower than the temperature chamber of the OCXO1, the temperature control of the temperature chamber in the OCXO1 can be performed stably and accurately. It should be noted that the temperature inside the outer case 6 is normally not lower than the ZTC temperature by 25 ° C. or more.

  For example, if the ZTC temperature of the crystal unit of OCXO1 is 50 ° C., the Peltier element control circuit increases the current of the Peltier element 3 so that the temperature inside the outer case 6 is about 30 ° C. (30 ° C. ± α ° C.). Control the sheath direction. The width of the temperature range (value of α) is appropriately set according to the use of the oscillator, required characteristics, and the like, and is set to 1 to 2 ° C., for example.

  Furthermore, the space in the outer case 6 may be in a vacuum or a state close to a vacuum, thereby making it difficult to transmit the influence of the external environment temperature of the outer case 6 to the OCXO 1 and further improving the temperature frequency characteristics. It can be done.

[Peltier element control circuit: Fig. 2]
Here, the Peltier element control circuit will be described with reference to FIG. FIG. 2 is a schematic explanatory diagram of a Peltier element control circuit mounted on the Peltier element temperature control circuit board 4.
As shown in FIG. 2, the Peltier element control circuit is mounted on the Peltier element temperature control circuit board 4 and includes a temperature sensor 41 and a control unit 42.
The Peltier element 3 is thermally coupled to the Peltier element temperature control circuit board 4 and the OCXO 1.

  The temperature sensor 41 detects the ambient temperature and outputs temperature data to the control unit 42. The place where the temperature sensor 41 is mounted is not a place that is directly affected by the heat generation / absorption of the Peltier element 3, but a place where the space temperature in the outer case 6 can be monitored as accurately as possible.

The control unit 42 is configured by a microcomputer or the like, controls the current flowing through the Peltier element 3, and heats or cools the Peltier element temperature control circuit board 4 side of the Peltier element 3 so that the inside of the outer case 6 is in a desired temperature range. To do.
That is, the control unit 42 controls the direction and magnitude of the current flowing through the Peltier element 3 based on the preset temperature range set in advance and the temperature data input from the temperature sensor 41. For example, the control unit 42 controls the current by controlling a switch that switches the direction of the current and a resistance value on the wiring.

For example, the control unit 42 stores in advance switch and resistance value control data corresponding to the input temperature data in accordance with the set temperature range, and based on the control data corresponding to the input temperature data. Control the current.
Specifically, when the temperature data is lower than the lower limit of the set temperature range (or below the lower limit), the control unit 42 heats the Peltier element temperature control circuit board 4 side of the Peltier element 3. Thus, when the current of the Peltier element 3 is controlled and higher than the upper limit of the temperature range (or higher than the upper limit), the control unit 42 controls to cool the Peltier element temperature control circuit board 4 side.

  If the configuration is desired to be simple, the control unit 42 may simply control the Peltier element temperature control circuit board 4 to cool when the temperature data is higher than the upper limit of the temperature range. Good. It is possible to prevent the temperature around the OCXO1 from becoming high and the temperature control of the OCXO1 from becoming unstable.

As described above, the set temperature range is a temperature that is 10 ° C. or more lower than the ZTC temperature of the crystal unit of the OCXO 1 and is set in the control unit 42 in advance.
Since the temperature sensor 41 is provided on the Peltier element temperature control circuit board 4, the temperature inside the outer case 6 may not be detected accurately. Therefore, a correlation (correction value) between the temperature of the space in the outer case 6 and the temperature data of the temperature sensor 41 is experimentally obtained in advance, and a value obtained by correcting the temperature data can be used for current control.

[Temperature characteristics of AT-cut quartz crystal: Fig. 3]
Here, the temperature characteristics of the AT cut crystal resonator used in the OCXO1 crystal resonator will be described with reference to FIG. FIG. 3 is an explanatory diagram showing an example of temperature characteristics of an AT-cut quartz resonator.
The characteristic indicated by the dotted line in FIG. 3 is that of a crystal resonator used in a conventional oscillator, and the ZTC temperature is 80 ° C. to 90 ° C. The three characteristics represent the characteristics of a crystal resonator with ZTC temperatures of 80 ° C., 85 ° C., and 90 ° C., respectively.
As described above, conventionally, a crystal resonator having a ZTC temperature higher than the upper limit of the use environment temperature (for example, −20 ° C. to 70 ° C.) is used, and temperature control is performed using the thermostatic chamber so that the ZTC temperature is reached.

The crystal resonator used in the OCXO1 of this oscillator has the characteristics shown by the solid line in FIG. 3, and the ZTC temperature is 45 ° C. to 55 ° C. The three characteristics represent the characteristics of a crystal resonator with ZTC temperatures of 45 ° C., 50 ° C., and 55 ° C., respectively.
The characteristics of the crystal resonator with a ZTC temperature of 45 ° C. to 55 ° C. used in this oscillator are more gradual than those of the crystal resonator with a ZTC temperature of 80 ° C. to 90 ° C. Are controlled with the same temperature range, a better frequency-temperature characteristic can be obtained than before.

  By using a crystal unit whose ZTC temperature is about 35 ° C. lower than that of the prior art, the temperature difference associated with power on / off can be reduced, and the thermal stress caused by heat cycle can be reduced. By prolonging the time until a crack is generated, the life of the oscillator can be extended, and the long-term reliability can be improved.

  For example, when the use environment temperature is −20 ° C. and a crystal resonator with a ZTC temperature of 90 ° C. is used, the temperature difference (ΔT) is 110 ° C., but when a crystal resonator with a ZTC temperature of 50 ° C. is used. ΔT = 70 ° C., and the temperature range to which the heat cycle is applied can be reduced by about 36%.

  Furthermore, in this oscillator, by providing the Peltier element 3 and the Peltier element control circuit, the temperature inside the outer case 6 that is the ambient environment of the OCXO 1 is stabilized in the OCXO 1 according to the ZTC temperature of the crystal resonator. By controlling by heating or cooling to a temperature range in which control can be performed (temperature range lower by 10 ° C. to 20 ° C. than the ZTC temperature), the output frequency can be further stabilized.

[Process of Peltier device control circuit: FIG. 4]
Next, processing of the control unit 42 of the Peltier element control circuit will be described with reference to FIG. FIG. 4 is a flowchart showing the processing of the control unit of the Peltier element control circuit.
As shown in FIG. 4, the control unit 42 of the Peltier device control circuit stores the temperature range inside the outer case 6 when it is set (100). Here, the set temperature range is T1 (° C.) or more and less than T2 (° C.) (T1 ≦ t <T2, t is a detection temperature), and is a temperature that is 10 ° C. or more lower than the ZTC temperature of the crystal unit used in OCXO1. It is a range.
For example, when the ZTC temperature is 50 ° C. and the control temperature width (α) is 1 ° C., the temperature range in the case is 50 ± 1 ° C. and is not less than 49 ° C. and less than 51 ° C.

When the detected temperature data (t) is input from the temperature sensor 41 (102), the control unit 42 compares the detected temperature data with the set temperature range (104).
When the detected temperature is lower than the lower limit value of the temperature range (when t <T1), the control unit 42 controls the current of the Peltier element 3 so as to heat the Peltier element temperature control circuit board 4 side. 102. At this time, the magnitude of the current may be controlled according to the difference between the detected temperature data (t) and the lower limit value (T1) of the set temperature range. When the difference is large, the current value is increased so as to increase the heat generation amount.

If the detected temperature data is within the temperature range in the process 104 (when T1 ≦ t <T2), the control unit 42 proceeds to the process 102 as it is.
If the detected temperature data is equal to or higher than the upper limit value of the temperature range in process 104 (when t ≧ T2), the control unit 42 supplies the current of the Peltier element 3 to cool the Peltier element temperature control circuit board 4 side. Control. Here, the magnitude of the current may be controlled in accordance with the difference between the detected temperature data (t) and the upper limit value (T2) of the set temperature range. When the difference is large, the current value in the opposite direction to that in the case of heat generation is increased so as to increase the endothermic amount.
In this way, the processing in the control unit 42 of the Peltier device control circuit is performed.

[Effect of the embodiment]
According to the oscillator according to the embodiment of the present invention, the OCXO 1 in which the crystal vibration having a ZTC temperature of 45 ° C. to 55 ° C. is mounted in the sealed outer case 6 and the Peltier element for heating or cooling the outer case 6. 3 and a Peltier element temperature control circuit board 4 on which a Peltier element control circuit for controlling the operation of the Peltier element 3 is mounted. The Peltier element is sandwiched between the OCXO 1 and the Peltier element temperature control circuit board 4. The OCXO1 controls the temperature of the thermostatic chamber to the ZTC temperature of the crystal resonator, and the Peltier element control circuit has a temperature in the case of 25 ° C. to 35 ° C., which is 10 ° C. higher than the ZTC temperature of the crystal resonator. Since the oscillator controls the current flowing through the Peltier element 3 so that the temperature is low, the width of the temperature change applied by the heat cycle is reduced, and the solder 5 is Peltier so that the temperature in the outer case 6 corresponding to the periphery of the OCXO 1 is 10 ° C. or more lower than the ZTC temperature that is the target temperature of the OCXO 1 constant temperature bath. By controlling the element 3 by heating or cooling, there is an effect that the temperature control of the OCXO 1 can be performed efficiently and accurately, and the output frequency can be stabilized.

  Also, according to this oscillator, since it operates at a lower temperature than in the past, the amount of heat released from the oscillator can be reduced, and the oscillator can be used as a device and apparatus that can cause a rise in temperature. There is an effect that can be enlarged.

  Further, according to the present oscillator, since the inside of the outer case 6 is in a vacuum or a state close to a vacuum, the effect of the external environment temperature on the OCXO 1 can be further reduced, and the output frequency can be stabilized. is there.

  Further, according to the present oscillator, the control unit 42 of the Peltier device control circuit stores the control data for controlling the current so that the inside of the outer case 6 is set to the set temperature range in association with the detected temperature. Since the control is performed in accordance with the control data corresponding to the input temperature data, the combination of the temperature range in the outer case 6, the detected temperature, and the control data is set according to the ZTC temperature of the crystal resonator. If it is stored, a highly stable oscillator can be realized by the same configuration and operation as the above embodiment, and various crystal resonators having different ZTC temperatures can be mounted, and an oscillator according to the application and purpose is provided. There is an effect that can.

  The present invention is particularly suitable for an oscillator capable of improving heat cycle resistance and obtaining good frequency temperature characteristics.

  1 ... OCXO, 2 ... inner cover, 3 ... Peltier element, 4 ... Peltier element temperature control circuit board, 5 ... solder, 6 ... outer cover, 7 ... lid, 8 ... pin

Claims (6)

An oscillator equipped with a crystal oscillator with a thermostatic bath,
A Peltier element that heats or cools depending on the current,
A Peltier element control circuit that is provided on a substrate and controls the Peltier element;
A case in which the thermostatic bath crystal oscillator, the Peltier element, and the Peltier element control circuit are hermetically sealed,
The Peltier element is sandwiched and mounted between the thermostatted crystal oscillator and the substrate,
The crystal oscillator with a thermostatic chamber includes a crystal resonator having a zero temperature coefficient point of 45 ° C. to 55 ° C., and a temperature control circuit that controls the temperature of the thermostatic chamber to be the zero temperature coefficient point of the crystal resonator,
The Peltier device control circuit controls the current of the Peltier device so that the temperature in the case is lower than the zero temperature coefficient point of the crystal resonator in a range of 10 ° C. to 25 ° C. Oscillator.   The oscillator according to claim 1, wherein the Peltier device control circuit controls the temperature in the case in a range of 25 ° C to 35 ° C.   The Peltier device control circuit includes a temperature sensor for detecting the temperature in the case, and when the detected temperature is higher than a set temperature range, the current is controlled so that the Peltier device cools the inside of the case. The oscillator according to claim 1 or 2.   4. The oscillator according to claim 3, wherein the Peltier element control circuit controls the current so that the Peltier element heats the case when the detected temperature is lower than a preset temperature range.   The Peltier device control circuit stores control data for controlling a current corresponding to a set temperature range and a detected temperature, and controls the current based on the control data corresponding to the detected temperature. Item 5. The oscillator according to Item 3 or 4. Oscillator according to any one of claims 1 to 5 in the case, characterized in that a state close to a vacuum or vacuum.

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